A Novel, Pan-PDE Inhibitor Exerts Anti-Fibrotic Effects in Human Lung Fibroblasts via Inhibition of TGF-β Signaling and Activation of cAMP/PKA Signaling

Transcriptomics reveals age-related changes in ion transport-related factors in yak lungs

Yaks inhabit high-altitude, low-oxygen regions, where ion transport functions play a crucial role in maintaining intracellular and extracellular ionic balance and regulating pulmonary vascular tension. These functions affect pulmonary ventilation and blood flow rate, aiding tissue development and enhancing oxygen transfer efficiency, thus facilitating better adaptation to hypoxic environments. To investigate the regulatory mechanisms of ion transport-related factors on the growth and development of yak lungs, we employed RNA sequencing (RNA-seq)for sequencing the transcriptome in the lung tissues of neonatal (1-day-old), juvenile (1-year-old), and adult (4-year-old) yaks. We also performed differential gene expression and functional analyses. The results yielded 26 genes associated with ion transport, mainly enriched in the salivary and pancreatic secretion pathways. Finally, we used several methods including quantitative polymerase chain reaction (qRT-PCR), and Western blotting (WB), immunohistochemical (IHC) and immunofluorescence (IF) staining to determine the distribution of the expression of the ion transport genes FOXI1, KCNMA1, and SLC12A2 in yak lung tissues. qRT-PCR and WB results indicated that mRNA and protein relative expression levels of FOXI1 and SLC12A2 were significantly higher in neonatal yaks than in juvenile and adult yaks (all p < 0.05), whereas those of KCNMA1 were significantly higher in adult yaks than in neonatal and juvenile yaks (all p < 0.05). IHC and IF results demonstrated that FOXI1, KCNMA1, and SLC12A2 were distributed among the epithelial mucosal layers (including ciliated, goblet, and Clara cells) of the yaks' bronchi and their branches in the lungs across different age groups of yak. Therefore, our results suggested that FOXI1, KCNMA1, and SLC12A2 may be strongly associated with the development and aging processes in yak lungs. These results provide insights into the molecular mechanisms underlying the yak's adaptation to high-altitude environments and valuable references for further research.

Investigating rutin as a potential transforming growth factor-β type I receptor antagonist for the inhibition of bleomycin-induced lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic lung condition characterized by the abnormal regulation of extracellular matrix (ECM) and epithelial-mesenchymal transition (EMT). In this study, we investigated the potential of rutin, a natural flavonoid, in attenuating transforming growth factor-β (TGF-β)-induced ECM regulation and EMT through the inhibition of the TGF-β type I receptor (TβRI)-mediated suppressor of mothers against decapentaplegic (SMAD) signaling pathway. We found that non-toxic concentrations of rutin attenuated TGF-β-induced ECM-related genes, including fibronectin, elastin, collagen 1 type 1, and TGF-β, as well as myoblast differentiation from MRC-5 lung fibroblast cells accompanied by the downregulation of α-smooth muscle actin. Rutin also inhibited TGF-β-induced EMT processes, such as wound healing, migration, and invasion by regulating EMT-related gene expression. Additionally, rutin attenuated bleomycin-induced lung fibrosis in mice, thus providing a potential therapeutic option for IPF. The molecular docking analyses in this study predict that rutin occludes the active site of TβRI and inhibits SMAD-mediated fibrotic signaling pathways in lung fibrosis. These findings highlight the potential of rutin as a promising anti-fibrotic prodrug for lung fibrosis and other TGF-β-induced fibrotic and cancer-related diseases; however, further studies are required to validate its safety and effectiveness in other experimental models.

The mechanism of Shenlong Jianji treatment of idiopathic pulmonary fibrosis inhibits fibroblast-to-myofibroblast transformation via the TGF-β1/smads signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Shenlong Jianji (SLJJ) is a Chinese herbal compound composed of traditional medicines for supplementing Qi, nourishing Yin, promoting blood circulation, and removing obstruction in channels. It is widely used to treat idiopathic pulmonary fibrosis (IPF) in China. However, the underlying mechanism of SLJJ remains unclear.

AIM OF THIS STUDY

To elucidate the efficacy and mechanisms of SLJJ in the treatment of IPF through in vivo and in vitro experiments.

MATERIAL AND METHODS

84 Wistar rats were randomly and equally divided into 7 groups: the control group (CTRL), the sham operation group (SHAM), the model group (IPF), the low dose of SLJJ group (L-SLJJ), the middle dose of SLJJ group (M-SLJJ), the high dose of SLJJ group (H-SLJJ), and the pirfenidone group (PFD). The rats in the CTRL, SHAM, and IPF groups were given normal saline each time for 28 days; the SLJJ groups were given Shenlong Jianji (9 g kg-1·d-1, 18 g kg-1·d-1, 36 g kg-1·d-1), and pirfenidone was administered as a sequential dose. After 28 days, the general condition of the rats was evaluated, and samples were collected. The lung coefficient was measured. The pathological changes of lung in each group were observed by H&E staining and Masson staining. α-SMA, collagen 1, and E-cadherin proteins were detected by immunohistochemistry. α-SMA, collagen 1, vimentin, E-cadherin, N-cadherin, TGF-β1, smad2, and smad3 proteins were detected by WB in vivo.In vitro, A scratch test was used to assess the ratio of cell migration. α-SMA, vimentin, E-cadherin, and N-cadherin protein levels were evaluated by a cellular immunofluorescence assay. TGF-β1/smads signaling pathway was detected by WB. HPLC-Q-TOF/MS analysis was used to identify the active compounds in the SLJJ. Molecular docking determined the free binding energy of the compound with the TGF-β1 protein.

RESULTS

SLJJ significantly improved the respiratory symptoms, heart rate, mental state, and food intake of IPF group rats and decreased the lung coefficient. In the IPF group, inflammatory cells were infiltrated, and the thickened alveoli wall and alveoli collapse were shown, while significantly alleviating pathological changes in the SLJJ and PFD groups. Masson staining showed that SLJJ and PFD decreased the collagen expression. Immunohistochemical results showed that the expressions of α-SMA, collagen 1, and N-cadherin decreased in the SLJJ and PFD groups, while E-cadherin increased significantly compared with the IPF group. SLJJ regulates TGF-β1/smads signaling pathway proteins in vivo. SLJJ decreased the ratio of migration in HFL-1 cells; SLJJ reduced the fluorescence intensity of α-SMA, vimentin, and N-cadherin and increased the fluorescence intensity of E-cadherin in primary rat lung (PRL) fibroblast cells and HFL-1 cells. WB results showed that SLJJ significantly down-regulated α-SMA, Vimentin, N-cadherin, TGF-β1, smad2, and p-smad2/3 proteins expression and up-regulated E-cadherin protein expression in vitro, whereas SRI-011381 (a TGF-β1 agonist) antagonized the effects of SLJJ.

CONCLUSION

SLJJ inhibits idiopathic pulmonary fibrosis. The TGF- β1/Smads signaling pathway can be the target of SLJJ, which inhibits fibroblast-to-myofibroblast transformation and is expected to be a new drug for the treatment of IPF.

Potential Rheumatoid Arthritis-Associated Interstitial Lung Disease Treatment and Computational Approach for Future Drug Development

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by swelling in at least one joint. Owing to an overactive immune response, extra-articular manifestations are observed in certain cases, with interstitial lung disease (ILD) being the most common. Rheumatoid arthritis-associated interstitial lung disease (RA-ILD) is characterized by chronic inflammation of the interstitial space, which causes fibrosis and the scarring of lung tissue. Controlling inflammation and pulmonary fibrosis in RA-ILD is important because they are associated with high morbidity and mortality. Pirfenidone and nintedanib are specific drugs against idiopathic pulmonary fibrosis and showed efficacy against RA-ILD in several clinical trials. Immunosuppressants and disease-modifying antirheumatic drugs (DMARDs) with anti-fibrotic effects have also been used to treat RA-ILD. Immunosuppressants moderate the overexpression of cytokines and immune cells to reduce pulmonary damage and slow the progression of fibrosis. DMARDs with mild anti-fibrotic effects target specific fibrotic pathways to regulate fibrogenic cellular activity, extracellular matrix homeostasis, and oxidative stress levels. Therefore, specific medications are required to effectively treat RA-ILD. In this review, the commonly used RA-ILD treatments are discussed based on their molecular mechanisms and clinical trial results. In addition, a computational approach is proposed to develop specific drugs for RA-ILD.

cAMP-PKA/EPAC signaling and cancer: the interplay in tumor microenvironment

Cancer is a complex disease resulting from abnormal cell growth that is induced by a number of genetic and environmental factors. The tumor microenvironment (TME), which involves extracellular matrix, cancer-associated fibroblasts (CAF), tumor-infiltrating immune cells and angiogenesis, plays a critical role in tumor progression. Cyclic adenosine monophosphate (cAMP) is a second messenger that has pleiotropic effects on the TME. The downstream effectors of cAMP include cAMP-dependent protein kinase (PKA), exchange protein activated by cAMP (EPAC) and ion channels. While cAMP can activate PKA or EPAC and promote cancer cell growth, it can also inhibit cell proliferation and survival in context- and cancer type-dependent manner. Tumor-associated stromal cells, such as CAF and immune cells, can release cytokines and growth factors that either stimulate or inhibit cAMP production within the TME. Recent studies have shown that targeting cAMP signaling in the TME has therapeutic benefits in cancer. Small-molecule agents that inhibit adenylate cyclase and PKA have been shown to inhibit tumor growth. In addition, cAMP-elevating agents, such as forskolin, can not only induce cancer cell death, but also directly inhibit cell proliferation in some cancer types. In this review, we summarize current understanding of cAMP signaling in cancer biology and immunology and discuss the basis for its context-dependent dual role in oncogenesis. Understanding the precise mechanisms by which cAMP and the TME interact in cancer will be critical for the development of effective therapies. Future studies aimed at investigating the cAMP-cancer axis and its regulation in the TME may provide new insights into the underlying mechanisms of tumorigenesis and lead to the development of novel therapeutic strategies.

Photobiomodulation therapy at 632 nm wavelength ameliorates intrauterine adhesion via activation of cAMP/PKA/CREB pathway

Intrauterine adhesion (IUA), a major cause of uterine infertility, is pathologically characterized by endometrial fibrosis. Current treatments for IUA have poor efficacy with high recurrence rate, and restoring uterine functions is difficult. We aimed to determine the therapeutic efficacy of photobiomodulation (PBM) therapy on IUA and elucidate its underlying mechanisms. A rat IUA model was established via mechanical injury, and PBM was applied intrauterinely. The uterine structure and function were evaluated using ultrasonography, histology, and fertility tests. PBM therapy induced a thicker, more intact, and less fibrotic endometrium. PBM also partly recovered endometrial receptivity and fertility in IUA rats. A cellular fibrosis model was then established with human endometrial stromal cells (ESCs) cultured in the presence of TGF-β1. PBM alleviated TGF-β1-induced fibrosis and triggered cAMP/PKA/CREB signaling in ESCs. Pretreatment with the inhibitors targeting this pathway weakened PBM's protective efficacy in the IUA rats and ESCs. Therefore, we conclude that PBM improved endometrial fibrosis and fertility via activating cAMP/PKA/CREB signaling in IUA uterus. This study sheds more lights on the efficacy of PBM as a potential treatment for IUA.

CRTC2 activates the epithelial-mesenchymal transition of diabetic kidney disease through the CREB-Smad2/3 pathway

BACKGROUND

Epithelial-mesenchymal transition (EMT) plays a key role in tubulointerstitial fibrosis, which is a hallmark of diabetic kidney disease (DKD). Our previous studies showed that CRTC2 can simultaneously regulate glucose metabolism and lipid metabolism. However, it is still unclear whether CRTC2 participates in the EMT process in DKD.

METHODS

We used protein‒protein network (PPI) analysis to identify genes that were differentially expressed during DKD and EMT. Then, we constructed a diabetic mouse model by administering STZ plus a high-fat diet, and we used HK-2 cells that were verified to confirm the bioinformatics research results. The effects that were exerted by CRTC2 on epithelial-mesenchymal transition in diabetic kidney disease through the CREB-Smad2/3 signaling pathway were investigated in vivo and in vitro by real-time PCR, WB, IHC and double luciferase reporter gene experiments.

RESULTS

First, bioinformatics research showed that CRTC2 may promote EMT in diabetic renal tubules through the CREB-Smad2/3 signaling pathway. Furthermore, the Western blotting and real-time PCR results showed that CRTC2 overexpression reduced the expression of E-cadherin in HK-2 cells. The CRTC2 and α-SMA levels were increased in STZ-treated mouse kidneys, and the E-cadherin level was reduced. The luciferase activity of α-SMA, which is the key protein in EMT, was sharply increased in response to the overexpression of CRTC2 and decreased after the silencing of CREB and Smad2/3. However, the expression of E-cadherin showed the opposite trends. In the real-time PCR experiment, the mRNA expression of α-SMA increased significantly when CRTC2 was overexpressed but partially decreased when CREB and Smad2/3 were silenced. However, E-cadherin expression showed the opposite result.

CONCLUSION

This study demonstrated that CRTC2 activates the EMT process via the CREB-Smad2/3 signaling pathway in diabetic renal tubules.

A phosphodiesterase-4 inhibitor reduces lung inflammation and fibrosis in a hamster model of SARS-CoV-2 infection

Introduction

The Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) infection involves pulmonary inflammation that can progress to acute respiratory distress syndrome, a primary cause of lung damage/fibrosis in patients with Coronavirus Disease-2019 (COVID-19). Currently, there is no efficacious therapy available to alleviate lung fibrosis in COVID-19 cases. In this proof-of-concept study, we evaluated the effect of CC-11050, a small molecule phosphodiesterase-4 inhibitor, in dampening lung inflammation and fibrosis in a hamster model of SARS-CoV-2 infection.

Methods

Following intranasal inoculation with SARS-CoV-2/WA- 1/2000 strain, hamsters were treated with CC-11050 or placebo by gavage from day-1 until day-16 post-infection (dpi). Animals were monitored for body weight changes, virus titers, histopathology, fibrotic remodeling, cellular composition in the lungs between 2 and 16 dpi.

Results

We observed significant reduction in lung viral titer with concomitant reduction in inflammation and fibrotic remodeling in CC-11050 treated hamsters compared to untreated animals. The reductions in immunopathologic manifestations were associated with significant downregulation of inflammatory and fibrotic remodeling gene expression, reduced infiltration of activated monocytes, granulocytes, and reticular fibroblasts in CC-11050 treated animals. Cellular studies indicate a link between TNF-α and fibrotic remodeling during CC-11050 therapy.

Discussion

These findings suggest that CC-11050 may be a potential host-directed therapy to dampen inflammation and fibrosis in COVID-19 cases.

Activation of TRPA1 in Bladder Suburothelial Myofibroblasts Counteracts TGF-β1-Induced Fibrotic Changes

The activation of the transient receptor potential ankyrin 1 (TRPA1) channel has anti-fibrotic effects in the lung and intestine. Suburothelial myofibroblasts (subu-MyoFBs), a specialized subset of fibroblasts in the bladder, are known to express TRPA1. However, the role of the TRPA1 in the development of bladder fibrosis remains elusive. In this study, we use the transforming growth factor-β1 (TGF-β1) to induce fibrotic changes in subu-MyoFBs and assess the consequences of TRPA1 activation utilizing RT-qPCR, western blotting, and immunocytochemistry. TGF-β1 stimulation increased α-SMA, collagen type I alpha 1 chain(col1A1), collagen type III (col III), and fibronectin expression, while simultaneously suppressing TRPA1 in cultured human subu-MyoFBs. The activation of TRPA1, with its specific agonist allylisothiocyanate (AITC), inhibited TGF-β1-induced fibrotic changes, and part of these inhibition effects could be reversed by the TRPA1 antagonist, HC030031, or by reducing TRPA1 expression via RNA interference. Furthermore, AITC reduced spinal cord injury-induced fibrotic bladder changes in a rat model. The increased expression of TGF-β1, α-SMA, col1A1 and col III, and fibronectin, and the downregulation of TRPA1, were also detected in the mucosa of fibrotic human bladders. These findings suggest that TRPA1 plays a pivotal role in bladder fibrosis, and the negative cross talk between TRPA1 and TGF-β1 signaling may represent one of the mechanisms underlying fibrotic bladder lesions.

Phosphodiesterase type 10A inhibitor attenuates lung fibrosis by targeting myofibroblast activation

Pulmonary fibrosis (PF) is a fatal and irreversible respiratory disease accompanied by excessive fibroblast activation. Previous studies have suggested that cAMP signaling pathway and cGMP-PKG signaling pathway are continuously down-regulated in lung fibrosis, whereas PDE10A has a specifically expression in fibroblasts/myofibroblasts in lung fibrosis. In this study, we demonstrated that overexpression of PDE10A induces myofibroblast differentiation, and papaverine, as a PDE10A inhibitor used for vasodilation, inhibits myofibroblast differentiation in human fibroblasts, Meanwhile, papaverine alleviated bleomycin-induced pulmonary fibrosis and amiodarone-induced oxidative stress, papaverine downregulated VASP/β-catenin pathway to reduce the myofibroblast differentiation. Our results first demonstrated that papaverine inhibits TGFβ1-induced myofibroblast differentiation and lung fibrosis by VASP/β-catenin pathway.

Inhaled pan-phosphodiesterase inhibitors ameliorate ovalbumin-induced airway inflammation and remodeling in murine model of allergic asthma

Asthma is a heterogeneous, chronic respiratory disease characterized by airway inflammation and remodeling. Phosphodiesterase (PDE) inhibitors represent one of the intensively studied groups of potential anti-asthmatic agents due to their affecting both airway inflammation and remodeling. However, the effect of inhaled pan-PDE inhibitors on allergen induced asthma has not been reported to date. In this study we investigated the impact of two, representative strong pan-PDE inhibitors from the group of 7,8-disubstituted derivatives of 1,3-dimethyl-3,7-dihydro-1H-purine-2,6-dione: compound 38 and 145, on airway inflammation and remodeling in murine model of ovalbumin (OVA)-challenged allergic asthma. Female Balb/c mice were sensitized and challenged with OVA, 38 and 145 were administrated by inhalation, before each OVA challenge. The inhaled pan-PDE inhibitors markedly reduced the OVA-induced airway inflammatory cell infiltration, eosinophil recruitment, Th2 cytokine level in bronchoalveolar lavage fluid, as well as both, total and OVA-specific IgE levels in plasma. In addition, inhaled 38 and 145 decreased many typical features of airway remodeling, including goblet cell metaplasia, mucus hypersecretion, collagen overproduction and deposition, as well as Tgfb1, VEGF, and α-SMA expression in airways of allergen challenged mice. We also demonstrated that both 38 and 145 alleviate airway inflammation and remodelling by inhibition of the TGF-β/Smad signaling pathway activated in OVA-challenged mice. Taken together, these results suggest that the investigated pan-PDE inhibitors administered by inhalation are dual acting agents targeting both airway inflammation and remodeling in OVA-challenged allergic asthma and may represent promising, anti-asthmatic drug candidates.

Perspectives of PDE inhibitor on treating idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive interstitial lung disease (ILD) without an identifiable cause. If not treated after diagnosis, the average life expectancy is 3-5 years. Currently approved drugs for the treatment of IPF are Pirfenidone and Nintedanib, as antifibrotic drugs, which can reduce the decline rate of forced vital capacity (FVC) and reduce the risk of acute exacerbation of IPF. However these drugs can not relieve the symptoms associated with IPF, nor improve the overall survival rate of IPF patients. We need to develop new, safe and effective drugs to treat pulmonary fibrosis. Previous studies have shown that cyclic nucleotides participate in the pathway and play an essential role in the process of pulmonary fibrosis. Phosphodiesterase (PDEs) is involved in cyclic nucleotide metabolism, so PDE inhibitors are candidates for pulmonary fibrosis. This paper reviews the research progress of PDE inhibitors related to pulmonary fibrosis, so as to provide ideas for the development of anti-pulmonary fibrosis drugs.

In silico and in vitro ADME-Tox analysis and in vivo pharmacokinetic study of representative pan-PDE inhibitors from the group of 7,8-disubstituted derivatives of 1,3-dimethyl-7H-purine-2,6-dione

Phosphodiesterase (PDE) inhibitors represent a wide class of chemically different compounds that have been extensively studied in recent years. Their anti-inflammatory and anti-fibrotic effects are particularly desirable in the treatment of chronic respiratory diseases, including asthma and chronic obstructive pulmonary disease (COPD). Due to diversified expression of individual PDEs within cells and/or tissues as well as PDE signaling compartmentalization, pan-PDE inhibitors (compounds capable of simultaneously blocking various PDE subtypes) are of particular interest. Recently, a large group of 7,8-disubstituted derivatives of 1,3-dimethyl-7H-purine-2,6-dione (theophylline) was designed and synthesized. These compounds were characterized as potent pan-PDE inhibitors and their prominent anti-inflammatory and anti-fibrotic activity in vitro has been proved. Herein, we investigated a general in vitro safety profile and pharmacokinetic characteristics of two leading compounds from this group: a representative compound with N'-benzylidenebutanehydrazide moiety (38) and a representative derivative containing N-phenylbutanamide fragment (145). Both tested pan-PDE inhibitors revealed no cytotoxic, mutagenic, and genotoxic activity in vitro, showed moderate metabolic stability in mouse and human liver microsomes, as well as fell into the low or medium permeation category. Additionally, 38 and 145 revealed a lack of interaction with adenosine receptors, including A1, A2A, and A2B. Pharmacokinetic analysis revealed that both tested 7,8-disubstituted derivatives of 1,3-dimethyl-7H-purine-2,6-dione were effectively absorbed from the peritoneal cavity. Simultaneously, they were extensively distributed to mouse lungs and after intraperitoneal (i.p.) administration were detected in bronchoalveolar lavage fluid. These findings provide evidence that investigated compounds represent a new drug candidates with a favorable in vitro safety profile and satisfactory pharmacokinetic properties after a single i.p. administration. As the next step, further pharmacokinetic studies after multiple i.p. and p.o. doses will be conducted to ensure effective 38 and 145 serum and lung concentrations for a longer period of time. In summary, 7,8-disubstituted derivatives of 1,3-dimethyl-7H-purine-2,6-dione represent a promising compounds worth testing in animal models of chronic respiratory diseases, the etiology of which involves various PDE subtypes.

A miniaturized screening platform to identify novel regulators of extracellular matrix alignment

Extracellular matrix alignment contributes to metastasis in a number of cancers and is a known prognostic stromal factor; however, the mechanisms controlling matrix organization remain unclear. Cancer-associated fibroblasts (CAF) play a critical role in this process, particularly via matrix production and modulation of key signaling pathways controlling cell adhesion and contractility. Stroma normalization, as opposed to elimination, is a highly sought strategy, and screening for drugs that effectively alter extracellular matrix (ECM) alignment is a practical way to identify novel CAF-normalizing targets that modulate ECM organization. To meet this need, we developed a novel high-throughput screening platform in which fibroblast-derived matrices were produced in 384-well plates, imaged with automated confocal microscopy, and analyzed using a customized MATLAB script. This platform is a technical advance because it miniaturizes the assay, eliminates costly and time-consuming experimental steps, and streamlines data acquisition and analysis to enable high-throughput screening applications. As a proof of concept, this platform was used to screen a kinase inhibitor library to identify modulators of matrix alignment. A number of novel potential regulators were identified, including several receptor tyrosine kinases (c-MET, tropomyosin receptor kinase 1 (NTRK1), HER2/ERBB2) and the serine/threonine kinases protein kinase A, C, and G (PKA, PKC, and PKG). The expression of these regulators was analyzed in publicly available patient datasets to examine the association between stromal gene expression and patient outcomes.

Therapeutic Potential of the Combination of Pentoxifylline and Vitamin-E in Inflammatory Bowel Disease: Inhibition of Intestinal Fibrosis

Background: Although intestinal fibrosis is a consequence of recurrent inflammation in Inflammatory bowel disease (IBD), alleviating inflammation alone does not prevent the progression of fibrosis, suggesting that the development of direct anti-fibrotic agents is necessary. This study aimed to evaluate the anti-fibrotic properties of combination treatment with pentoxifylline (PTX) and vitamin E (Vit-E) on human primary intestinal myofibroblasts (HIMFs) and the therapeutic potential of the combination therapy in murine models of IBD. Methods: HIMFs were pretreated with PTX, Vit-E, or both, and incubated with TGF-β1. We performed Western blot, qPCR, collagen staining, and immunofluorescence to estimate the anti-fibrotic effects of PTX and Vit-E. The cytotoxicity of these was investigated through MTT assay. To induce murine models of IBD for in vivo study, C57BL/6 mice were treated with repeated cycles of dextran sulfate sodium (DSS), developing chronic colitis. We examined whether the combined PTX and Vit-E treatment would effectively ameliorate colonic fibrosis in vivo. Results: We found that the co-treatment with PTX and Vit-E suppressed TGF-β1-induced expression of fibrogenic markers, with decreased expression of pERK, pSmad2, and pJNK, more than either treatment alone in HIMFs. Neither PTX nor Vit-E showed any significant cytotoxicity in given concentrations. Consistently with the in vitro results, the co-administration with PTX and Vit-E effectively attenuated colonic fibrosis with recovery from thickening and shortening of colon in murine models of IBD. Conclusions: These findings demonstrated that the combination of PTX and Vit-E exhibits significant anti-fibrotic effects in both HIMFs and in vivo IBD models, providing a promising therapy for IBD.

Salt-inducible kinase 2 (SIK2) inhibitor ARN-3236 attenuates bleomycin-induced pulmonary fibrosis in mice

Background

Pulmonary fibrosis is a fatal lung disease with complex pathogenesis and limited effective therapies. Salt-inducible kinase 2 (SIK2) is a kinase that phosphorylates CRTCs and regulates many physiological processes. However, the role of SIK2 on pulmonary fibrosis remains unclear, and whether SIK2 inhibitor can attenuate pulmonary fibrosis is unknown.

Method

We subjected human fetal lung fibroblasts (HFLs) to transforming growth factor-β1 (5 ng/mL) for 12 h, and examined the expression of SIK2, CRTCs and pCRTCs in fibroblasts by western-blot. To address the roles of SIK2 and CRTCs involved in the progression of pulmonary fibrosis, HFLs were treated with a small-molecule inhibitor ARN-3236 or by siRNA-mediated knockdown of SIK2 expression. Pulmonary fibrosis model was established with mice by exposing to bleomycin, and assessed by H&E and Masson’s trichrome staining. COL1A and α-SMA distributions were detected in lung tissues by immunohistochemical staining.

Results

We discovered that SIK2 and phosphorylated-CRTC2 were expressed at a low basal level in normal lung tissues and quiescent fibroblasts, but increased in fibrotic lung tissues and activated fibroblasts. Inhibition of SIK2 by ARN-3236 prevented the fibroblasts differentiation and extracellular matrix expression in HFLs and attenuated bleomycin-induced pulmonary fibrosis in mice. Mechanistically, inactivation of SIK2 resulted in the dephosphorylation and nuclear translocation of CRTC2. Within the nucleus, CRTC2 binds to CREB, promoting CREB-dependent anti-fibrotic actions.

Conclusion

In conclusion, our results elucidated a previously unexplored role of SIK2 in pulmonary fibrosis, and identified SIK2 as a new target for anti-fibrosis medicines.

Pan-Phosphodiesterase Inhibitors Attenuate TGF-β-Induced Pro-Fibrotic Phenotype in Alveolar Epithelial Type II Cells by Downregulating Smad-2 Phosphorylation

Airway remodeling is a pathological process that accompanies many chronic lung diseases. One of the important players in this process are epithelial cells, which under the influence of pro-inflammatory and pro-fibrotic factors present in the airway niche, actively participate in the remodeling process by increasing extracellular matrix secretion, acquiring migration properties, and overproducing pro-fibrotic transducers. Here, we investigated the effect of three new 8-arylalkylamino- and 8-alkoxy-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl-N-(5-(tert-butyl)-2-hydroxyphenyl)butanamides (1, 2, and 3), representing prominent pan-phosphodiesterase (pan-PDE) inhibitors on transforming growth factor type β (TGF-β)-induced alveolar epithelial type II cells (A549 cell line) of a pro-fibrotic phenotype. Our results demonstrate for the first time the strong activity of pan-PDE inhibitors in the prevention of TGF-β-induced mesenchymal markers’ expression and A549 cells’ migration. We also showed an increased p-CREB and decreased p-Smad-2 phosphorylation in TGF-β-induced A549 cells treated with 1, 2, and 3 derivatives, thereby confirming a pan-PDE inhibitor mesenchymal phenotype reducing effect in alveolar epithelial type II cells via suppression of the canonical Smad signaling pathway. Our observations confirmed that PDE inhibitors, and especially those active against various isoforms involved in the airway remodeling, constitute an interesting group of compounds modulating the pro-fibrotic response of epithelial cells.

Betanin Dose-Dependently Ameliorates Allergic Airway Inflammation by Attenuating Th2 Response and Upregulating cAMP-PKA-CREB Pathway in Asthmatic Mice

Allergic asthma is a refractory disease that affects hundreds of millions of people worldwide. Betanin is a natural plant-derived nutrient and possesses health-promoting properties. The effects of betanin on allergic asthma remain unknown. Herein, the effects and mechanisms of betanin on allergic asthma were explored in ovalbumin (OVA)-induced BALB/c mice. Betanin in doses of 0, 20, 60, and 180 mg/kg was applied. Peripheral inflammatory cells, IgE, pulmonary pathology, T cell subsets, cytokine levels, protein expressions of the cAMP-PKA-CREB/CREM pathway, and gut microbial profile were measured. The 60 and 180 mg/kg/day betanin doses significantly downregulated IgE, eotaxin, eosinophil infiltration, mucus hyperproduction, and Th2. A 180 mg/kg/day betanin dose also significantly reduced percentages of Th17, Tc17, and Tc2 and Th2- and Th17-signature cytokines and upregulated the cAMP-PKA-CREB pathway. Additionally, 20 mg/kg/day betanin altered the gut microbial profile. In conclusion, betanin dose-dependently alleviated allergic asthma and upregulated the cAMP-PKA-CREB pathway in mice. This study provides a novel nutritional strategy to treat allergic asthma.

Fibroblast mechanotransduction network predicts targets for mechano-adaptive infarct therapies

Regional control of fibrosis after myocardial infarction is critical for maintaining structural integrity in the infarct while preventing collagen accumulation in non-infarcted areas. Cardiac fibroblasts modulate matrix turnover in response to biochemical and biomechanical cues, but the complex interactions between signaling pathways confound efforts to develop therapies for regional scar formation. We employed a logic-based ordinary differential equation model of fibroblast mechano-chemo signal transduction to predict matrix protein expression in response to canonical biochemical stimuli and mechanical tension. Functional analysis of mechano-chemo interactions showed extensive pathway crosstalk with tension amplifying, dampening, or reversing responses to biochemical stimuli. Comprehensive drug target screens identified 13 mechano-adaptive therapies that promote matrix accumulation in regions where it is needed and reduce matrix levels in regions where it is not needed. Our predictions suggest that mechano-chemo interactions likely mediate cell behavior across many tissues and demonstrate the utility of multi-pathway signaling networks in discovering therapies for context-specific disease states.

Arecoline Enhances Phosphodiesterase 4A Activity to Promote Transforming Growth Factor-β-Induced Buccal Mucosal Fibroblast Activation via cAMP-Epac1 Signaling Pathway

Chewing areca nut (betel quid) is strongly associated with oral submucous fibrosis (OSF), a pre-cancerous lesion. Among the areca alkaloids, arecoline is the main agent responsible for fibroblast proliferation; however, the specific molecular mechanism of arecoline affecting the OSF remains unclear. The present study revealed that arecoline treatment significantly enhanced Transforming growth factor-β (TGF-β)-induced buccal mucosal fibroblast (BMF) activation and fibrotic changes. Arecoline interacts with phosphodiesterase 4A (PDE4A) to exert its effects through modulating PDE4A activity but not PDE4A expression. PDE4A silence reversed the effects of arecoline on TGF-β-induced BMFs activation and fibrotic changes. Moreover, the exchange protein directly activated by cAMP 1 (Epac1)-selective Cyclic adenosine 3′,5′-monophosphate (cAMP) analog (8-Me-cAMP) but not the protein kinase A (PKA)-selective cAMP analog (N6-cAMP) remarkably suppressed α-smooth muscle actin(α-SMA) and Collagen Type I Alpha 1 Chain (Col1A1) protein levels in response to TGF-β1 and arecoline co-treatment, indicating that cAMP-Epac1 but not cAMP-PKA signaling is involved in arecoline functions on TGF-β1-induced BMFs activation. In conclusion, arecoline promotes TGF-β1-induced BMFs activation through enhancing PDE4A activity and the cAMP-Epac1 signaling pathway during OSF. This novel mechanism might provide more powerful strategies for OSF treatment, requiring further in vivo and clinical investigation.

Phosphodiesterase 4 inhibitors in diabetic nephropathy

Phosphodiesterase subtype 4 (PDE4) hydrolyzes cyclic AMP, a secondary messenger that mediates intracellular signaling, and plays key roles in inflammatory and fibrotic responses. Based on these significant anti-inflammatory effects, oral administration of PDE4 inhibitor is approved for the treatment of chronic obstructive pulmonary disease, atopic dermatitis, and psoriasis. However, PDE4 inhibition also has adverse effects, such as diarrhea, vomiting, dyspepsia, and headache. Therefore, the application of PDE4 inhibitors for chronic diseases, such as diabetes and its complications, has not yet been approved. Recent studies have reported the clinical benefits of pentoxifylline, a non-selective PDE inhibitor, in patients with kidney disease. The PDE4 inhibitor, roflumilast, also clearly ameliorates the symptoms of diabetes mellitus by improving hyperglycemia and insulin resistance. However, the beneficial effects of PDE4 inhibition on diabetic nephropathy have not yet been evaluated, and its potential mechanisms of action remain unknown. In this review, we discuss the beneficial effects of PDE4 inhibitors and their mechanisms of action using diabetes and DN models.

Synthesis and in vitro evaluation of anti-inflammatory, antioxidant, and anti-fibrotic effects of new 8-aminopurine-2,6-dione-based phosphodiesterase inhibitors as promising anti-asthmatic agents

Phosphodiesterase (PDE) inhibitors are currently an extensively studied group of compounds that can bring many benefits in the treatment of various inflammatory and fibrotic diseases, including asthma. Herein, we describe a series of novel N'-phenyl- or N'-benzylbutanamide and N'-arylidenebutanehydrazide derivatives of 8-aminopurine-2,6-dione (27-43) and characterized them as prominent pan-PDE inhibitors. Most of the compounds exhibited antioxidant and anti-inflammatory activity in lipopolysaccharide (LPS)-induced murine macrophages RAW264.7. The most active compounds (32-35 and 38) were evaluated in human bronchial epithelial cells (HBECs) derived from asthmatics. To better map the bronchial microenvironment in asthma, HBECs after exposure to selected 8-aminopurine-2,6-dione derivatives were incubated in the presence of two proinflammatory and/or profibrotic factors: transforming growth factor type β (TGF-β) and interleukin 13 (IL-13). Compounds 32-35 and 38 significantly reduced both IL-13- and TGF-β-induced expression of proinflammatory and profibrotic mediators, respectively. Detailed analysis of their inhibition preferences for selected PDEs showed high affinity for isoenzymes important in the pathogenesis of asthma, including PDE1, PDE3, PDE4, PDE7, and PDE8. The presented data confirm that structural modifications within the 7 and 8 positions of the purine-2,6-dione core result in obtaining preferable pan-PDE inhibitors which in turn exert an excellent anti-inflammatory and anti-fibrotic effect in the bronchial epithelial cells derived from asthmatic patients. This dual-acting pan-PDE inhibitors constitute interesting and promising lead structures for further anti-asthmatic agent discovery.

Perspective on Stem Cell Therapy in Organ Fibrosis: Animal Models and Human Studies

Tissue fibrosis is characterized by excessive deposition of extracellular matrix (ECM) components that result from the disruption of regulatory processes responsible for ECM synthesis, deposition, and remodeling. Fibrosis develops in response to a trigger or injury and can occur in nearly all organs of the body. Thus, fibrosis leads to severe pathological conditions that disrupt organ architecture and cause loss of function. It has been estimated that severe fibrotic disorders are responsible for up to one-third of deaths worldwide. Although intensive research on the development of new strategies for fibrosis treatment has been carried out, therapeutic approaches remain limited. Since stem cells, especially mesenchymal stem cells (MSCs), show remarkable self-renewal, differentiation, and immunomodulatory capacity, they have been intensively tested in preclinical studies and clinical trials as a potential tool to slow down the progression of fibrosis and improve the quality of life of patients with fibrotic disorders. In this review, we summarize in vitro studies, preclinical studies performed on animal models of human fibrotic diseases, and recent clinical trials on the efficacy of allogeneic and autologous stem cell applications in severe types of fibrosis that develop in lungs, liver, heart, kidney, uterus, and skin. Although the results of the studies seem to be encouraging, there are many aspects of cell-based therapy, including the cell source, dose, administration route and frequency, timing of delivery, and long-term safety, that remain open areas for future investigation. We also discuss the contemporary status, challenges, and future perspectives of stem cell transplantation for therapeutic options in fibrotic diseases as well as we present recent patents for stem cell-based therapies in organ fibrosis.

A new class of 5-HT1A receptor antagonists with procognitive and antidepressant properties

Aims: 5-HT1A receptor antagonists constitute a potential group of drugs in the treatment of CNS diseases. The aim of this study was to search for new procognitive and antidepressant drugs among amide derivatives of aminoalkanoic acids with 5-HT1A receptor antagonistic properties. Materials & methods: Thirty-three amides were designed and evaluated in silico for their drug-likeness. The synthesized compounds were tested in vitro for their 5-HT1A receptor affinity and functional profile. Moreover, their selectivity over 5-HT7, 5-HT2A and D2 receptors and ability to inhibit phosphodiesterases were evaluated. Results: A selected 5-HT1A receptor antagonist 20 (Ki = 35 nM, Kb = 4.9 nM) showed procognitive and antidepressant activity in vivo. Conclusion: Novel 5-HT1A receptor antagonists were discovered and shown as potential psychotropic drugs.

Expression profiling of ileal mucosa in asthma reveals upregulation of innate immunity and genes characteristic of Paneth and goblet cells

Background

The expression profiles of the intestinal mucosa have not been comprehensively investigated in asthma. We aimed to explore this in the Correlated Expression and Disease Association Research (CEDAR) patient cohort.

Methods

Differential expression analysis of ileal, transverse colon, and rectal biopsies were supplemented by a comparison of transcriptomes from platelets and leukocytes subsets, including CD4+, CD8+, CD14+, CD15+, and CD19+ cells. Asthma patients (n = 15) and controls (n = 15) had similar age (p = 0.967), body mass index (p = 0.870), similar numbers of females (80%) and smoking rates (13.3%).

Results

Significant differential expression was found in the ileum alone, and not in any other cell/tissue types. More genes were found to be overexpressed (1,150) than under-expressed (380). The most overexpressed genes included Fc Fragment of IgG Binding Protein (FCGBP, logFC = 3.01, pFDR = 0.015), Mucin 2 (MUC2, logFC = 2.78, pFDR = 0.015), and Alpha 1B Defensin (DEFA1B, logFC = 2.73, pFDR = 0.024). Gene ontology implicated the immune system, including interleukins 4 and 13, as well as antimicrobial peptides in this overexpression. There was concordance of gene over- (STAT1, XBP1) and underexpression (NELF, RARA) in asthma and Crohn’s disease ileum when our results were compared to another dataset (p = 3.66 × 10^–7).

Conclusion

Ileal mucosa in asthma exhibits a specific transcriptomic profile, which includes the overexpression of innate immune genes, mostly characteristic of Paneth and goblet cells, in addition to other changes that may resemble Crohn’s disease.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13223-021-00584-9.

Targeting Airway Smooth Muscle Hypertrophy in Asthma: An Approach Whose Time Has Come

Airway smooth muscle (ASM) cell dysfunction is an important component of several obstructive pulmonary diseases, particularly asthma. External stimuli such as allergens, dust, air pollutants, and change in environmental temperatures provoke ASM cell hypertrophy, proliferation, and migration without adequate mechanistic controls. ASM cells can switch between quiescent, migratory, and proliferative phenotypes in response to extracellular matrix proteins, growth factors, and other soluble mediators. While some aspects of airway hypertrophy and remodeling could have beneficial effects, in many cases these contribute to a clinical phenotype of difficult to control asthma. In this review, we discuss the factors responsible for ASM hypertrophy and proliferation in asthma, focusing on cytokines, growth factors, and ion transporters, and discuss existing and potential approaches that specifically target ASM hypertrophy to reduce the ASM mass and improve asthma symptoms. The goal of this review is to highlight strategies that appear ready for translational investigations to improve asthma therapy.

New Avenues for Phosphodiesterase Inhibitors in Asthma

Introduction

Phosphodiesterases (PDEs) are isoenzymes ubiquitously expressed in the lungs where they catalyse cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (GMP), which are fundamental second messengers in asthma, thereby regulating the intracellular concentrations of these cyclic nucleotides, their signaling pathways and, consequently, myriad biological responses. The superfamily of PDEs is composed of 11 families with a distinct substrate specificity, molecular structure and subcellular localization. Experimental studies indicate a possible role in asthma mainly for PDE3, PDE4, PDE5 and PDE7. Consequently, drugs that inhibit PDEs may offer novel therapeutic options for the treatment of this disease.

Areas Covered

In this article, we describe the progress made in recent years regarding the possibility of using PDE inhibitors in the treatment of asthma.

Expert Opinion

Many data indicate the potential benefits of PDE inhibitors as an add-on treatment especially in severe asthma due to their bronchodilator and/or anti-inflammatory activity, but no compound has yet reached the market as asthma treatment mainly because of their limited tolerability. Therefore, there is a growing interest in developing new PDE inhibitors with an improved safety profile. In particular, the research is focused on the development of drugs capable of interacting simultaneously with different PDEs, or to be administered by inhalation. CHF 6001 and RPL554 are the only molecules that currently are under clinical development but there are several new agents with interesting pharmacological profiles. It will be stimulating to assess the impact of such agents on individual treatable traits in specially designed studies.

Phosphodiesterase Inhibitors: Could They Be Beneficial for the Treatment of COVID-19?

In March 2020, the World Health Organization declared the severe acute respiratory syndrome corona virus 2 (SARS-CoV2) infection to be a pandemic disease. SARS-CoV2 was first identified in China and, despite the restrictive measures adopted, the epidemic has spread globally, becoming a pandemic in a very short time. Though there is growing knowledge of the SARS-CoV2 infection and its clinical manifestations, an effective cure to limit its acute symptoms and its severe complications has not yet been found. Given the worldwide health and economic emergency issues accompanying this pandemic, there is an absolute urgency to identify effective treatments and reduce the post infection outcomes. In this context, phosphodiesterases (PDEs), evolutionarily conserved cyclic nucleotide (cAMP/cGMP) hydrolyzing enzymes, could emerge as new potential targets. Given their extended distribution and modulating role in nearly all organs and cellular environments, a large number of drugs (PDE inhibitors) have been developed to control the specific functions of each PDE family. These PDE inhibitors have already been used in the treatment of pathologies that show clinical signs and symptoms completely or partially overlapping with post-COVID-19 conditions (e.g., thrombosis, inflammation, fibrosis), while new PDE-selective or pan-selective inhibitors are currently under study. This review discusses the state of the art of the different pathologies currently treated with phosphodiesterase inhibitors, highlighting the numerous similarities with the disorders linked to SARS-CoV2 infection, to support the hypothesis that PDE inhibitors, alone or in combination with other drugs, could be beneficial for the treatment of COVID-19.